Perforating gun having self-closing penetration holes

ABSTRACT

A perforating gun having an outer gun barrel, inside of which an inner barrel is coaxially arranged, carrying perforators that can be ignited by means of a detonating cord leading through the gun barrel and, after ignition, pierce the gun barrel in order to form penetration holes, wherein means are provided for automatically closing the penetration holes after the blast, said means being a swellable medium. In order to ensure that the swellable medium requires little space in the perforating gun and can be easily integrated into the perforating gun, the swellable medium is disposed in a laminary manner inside the perforating gun.

The invention relates to a perforation gun having an outer gun barrel inside of which an inner barrel is coaxially situated, and which bears perforators that are ignitable via a detonating fuse leading through the gun barrel, and which after ignition pierce the gun barrel to form penetration holes, wherein a means is provided for automatically closing the penetration holes after the shot, and this means is a swellable medium.

Such a perforation gun is described in EP 1 685 308 B1.

Perforation guns are used in deep hole Wasting in the crude oil and natural gas industry as well as in hydraulic engineering to tie the borehole to the storage horizon. The borehole generally contains a drill hole fluid, which may be an introduced fluid or the medium to be conveyed from the surrounding rock.

A perforation gun is composed of an outer gun barrel, inside of which perforators, usually hollow or projectile charges, are situated, and which shoot radially outwardly through the gun barrel in the case of ignition. The hollow charges are usually supported by a thin-walled support pipe which extends coaxially inside the gun barrel. Penetration holes remain in the gun barrel after the shot.

A problem with this method is that residual pieces and fragments of the perforators and of the components inside the gun barrel may fall into the borehole through the penetration holes after the shot. For this reason, as described in EP 1 685 308, means are provided for automatically closing the penetration holes after the shot, these means being cartridges containing a swellable two-component foam. These cartridges are situated in the gun barrel, and break up by means of the ignited detonating fuse, as the result of which foam emerges from the cartridges, swells up, and plugs the penetration holes.

The object of the invention is to improve a perforation gun according to the preamble of Claim 1 in such a way that the swellable medium requires little space and is easily integratable into the perforation gun. In one embodiment, it is the further aim that preferably no additional room is taken up in the perforation gun.

This object is achieved according to the invention in that the swellable medium is situated in a planar manner inside the perforation gun. Planar structures require less space, and are easily integratable into the perforation gun.

In one preferred embodiment, the swellable medium is provided as a coating in the perforation gun. A coating requires no additional room in the perforation gun, and therefore is easily integratable.

The coating is preferably situated on the interior of the gun barrel. Alternatively, the coating may be applied to an additional thin-walled pipe located coaxially between the outer gun barrel and the inner barrel. Both barrels are particularly suitable for a coating.

In another embodiment, the swellable medium is applied as a solid material, for example supplied from a roll by wrapping, to the gun barrel or an additional thin-wailed pipe which is located coaxially between the gun barrel and the inner barrel. Wrapping is a simple manual activity which is also cost-effective.

The swellable medium may also be applied only in the region of the penetration holes as a solid material, for example as a circular blank, to the gun barrel and/or an additional thin-walled pipe which is located coaxially between the gun barrel and the inner barrel. Circular blanks are easily manufactured and applied.

In another preferred embodiment, the swellable medium itself is a pipe or tube which is located coaxially between the outer gun barrel and the inner barrel.

In all embodiments, the swellable medium may be activated by igniting the perforators via contact with the borehole medium such as oil, gas, water, drilling fluids used in deep hole drilling, or by other borehole-related influences, whereby the swellable medium swells up and thus closes the penetration holes.

In one preferred embodiment, the swellable medium is composed of an elastomer compound which is activated on contact with, for example,

-   -   oil     -   gas     -   other types of hydrocarbons     -   water     -   borehole drilling fluids used in deep hole drilling     -   explosive gases from perforators,         and swells up, thus plugging the penetration holes.

The swellable medium may also be activated by matching the gun internal pressure to the pressure present in the borehole, which is generally much higher. This is achieved by properly penetrating the gun outer wall by means of the perforators which are ignited in the gun.

It is preferred to use a swellable planar medium inside a perforation gun having an outer gun barrel inside of witch an inner barrel is coaxially situated, and which bears perforators that are ignitable via a detonating fuse leading through the gun barrel, and which after ignition pierce the gun barrel to form penetration holes, wherein the swellable medium is activated by the ignition of the perforators via contact with the borehole medium such as oil, gas, water, drilling fluids used in deep hole drilling, or by other borehole-related influences, swells up, and thus doses the penetration holes.

The swellable medium may be provided as a coating in the perforation gun, applied as a solid material by wrapping, or may be a pipe or tube itself which is located coaxially between the outer gun barrel and the inner barrel.

The invention is characterized in that no “debris” (fragments from the perforators) falls into the borehole. No external intervention is necessary to close the penetration holes. 

1-12. (canceled)
 13. A perforation gun having an outer gun barrel inside of which an inner barrel is coaxially situated, and which bears perforators that are ignitable via a detonating fuse leading through the gun barrel and which after ignition pierce the gun barrel to form penetration holes, wherein a means is provided for automatically closing the penetration holes after the shot, and this means is a swellable medium, wherein the swellable medium is situated in a planar manner inside the perforation gun.
 14. A perforation gun according to claim 13, wherein the swellable medium is provided as a coating in the perforation gun.
 15. A perforation gun according to claim 14, wherein the coating is situated on the interior of the gun barrel.
 16. A perforation gun according to claim 14, wherein the coating is situated on an additional thin-walled pipe which is located coaxially between the outer gun barrel and the Inner barrel.
 17. A perforation gun according to claim 13, wherein the swellable medium is applied as a solid material, for example supplied from a roll by wrapping, to the gun barrel or an additional thin-walled pipe which is located coaxially between the gun barrel and the inner barrel.
 18. A perforation gun according to one of the preceding claims, wherein the swellable medium is applied only in the region of the penetration holes as a solid material, for example as a circular blank, to the gun barrel and/or an additional thin-walled pipe which is located coaxially between the gun barrel and the inner barrel.
 19. A perforation gun according to claim 13, wherein the swellable medium itself is a pipe or tube which is located coaxially between the outer gun barrel and the inner barrel.
 20. A perforation gun according to one of the preceding claims, wherein the swellable medium is activated by the ignition of the perforators via contact with the borehole medium such as oil, gas, water, drilling fluids used in deep hole drilling, or by other borehole-related influences, swells up, and thus closes the penetration holes.
 21. A method comprising providing swellable planar medium inside a perforation gun, having an outer gun barrel inside of which an inner barrel is coaxially situated, and which has perforators that ignite via a detonating fuse leading through the gun barrel, and after ignition pierce the gun barrel to form penetration holes, wherein the swellable medium is activated by the ignition of the perforators v a contact with the borehole medium such as oil, gas, water, drilling fluids used in deep hole drilling, or by other borehole-related influences, swells up, and thereby closes the penetration holes.
 22. The method according to according to claim 21, wherein the swellable medium is provided as a coating in the perforation gun.
 23. The method according to claim 21, wherein the swellable medium is applied as a solid material by wrapping.
 24. The method according to claim 21, wherein the swellable medium itself is a pipe or tube which is located coaxially between the outer gun barrel and the inner barrel. 